I have seen in my brother, who lives in the UK, how pale he has gotten since living there. You don't realise how big of an impact the sun has on your life unless you live without it for a while! Dangerous stuff if you don't get all of the vitamins in through your diet and environment.
Oh my, so it is not just a South African problem, haha! It really gets bad, as in the summer the houses traps heat, and in the winter it insulates the cold. Never in balance!